Problem 66 - Chemistry: The Central Science

Question

What is the empirical formula of glycogen? What is the unit that forms the basis of the glycogen polymer? What form of linkage joins these monomeric units?

Step-by-Step Solution

Answer

The empirical formula of glycogen is \(C_6H_{12}O_6\), as it is composed of glucose subunits with the same molecular formula. Glucose, a monosaccharide with the molecular formula \(C_6H_{12}O_6\), forms the basis of the glycogen polymer. The monomeric units of glucose in glycogen are connected through α-glycosidic linkages, with two types: α(1→4) and α(1→6). The α(1→4) linkages create a linear chain of glucose units, while the α(1→6) linkages are responsible for the branching structure of glycogen.

Step 1: Empirical formula of glycogen

Glycogen is a polysaccharide composed of glucose subunits. The empirical formula of glucose is \(C_6H_{12}O_6\). Since glycogen is a polymer of glucose, its empirical formula is the same as glucose, \(C_6H_{12}O_6\).

Step 2: Basic unit of glycogen polymer

Glycogen is composed of glucose molecules, so the basic unit forming the glycogen polymer is glucose. Glucose is a monosaccharide with the molecular formula \(C_6H_{12}O_6\).

Step 3: Linkage between monomeric units

Glycogen is a branched polymer of glucose, with the glucose monomers connected through α-glycosidic linkages. There are two types of α-glycosidic linkages in glycogen: α(1→4) and α(1→6). The majority of the glucose units in glycogen are connected through α(1→4) glycosidic linkages. These linkages are formed between the first and fourth carbon atoms in the glucose molecules. This linkage creates a linear chain of glucose units. The branching of the glycogen structure is due to the α(1→6) glycosidic linkage. This linkage occurs between the first carbon atom of one glucose molecule and the sixth carbon atom of another glucose molecule. This type of linkage is found approximately every 10 glucose residues along the linear chain, creating a highly branched structure for glycogen.